The primary goal of the Mass Spectrometry/Protein Microsequencing Core is to provide characterization of the complex biomolecules that are expressed and isolated through the research of Cancer Center members. Characterization often includes intact mass measurement, amino acid analysis, deglycosylation, reduction/alkylation followed by endoprotease digestion, peptide mapping of the digests, sequence determination (by N-terminal sequencing or LC/tandem mass spectrometry), and determination of sites and types of post-translational modifications. Other queries address the characterization of binding sites of small molecules and large molecules in complexes. Utilizing the state-of-the-art equipment available in this resource, differences in the structure and state of these molecules as they transition between native and disease states (cancer) may be probed. Recent Core enhancements include: (1.) The new AB-Biosystems Voyager DE-STR mass spectrometer, which is being used to provide direct mass measurements of intact oligonucleotides of up to 75 base lengths (non-duplex), intact glycoproteins, and phosphoproteins. (2.) The new AB-Biosystems Mariner mass spectrometer, which permits the direct LC/MS analysis of nucleosides and nucleotides by Fast LC/MS. Improved in-gel methods (for Coomassie and Silver-stained bands), combined with utilization of the Finnigan/Thermoquest LCQ and DECA quadrupole ion trap mass spectrometers, provide sub-picomole LC/tandem MS protein sequencing and protein identification. (3.) The addition of the new AB Procise N-terminal sequencer (high fmol to low pmol concentration range), which complements the LC/tandem MS efforts by permitting determination of the N-terminus on intact proteins and identification of amino acids that share the same mass. (4.) The new Dionex Amino Acid Analyzer, which allows the Core to provide protein quantity determination (high fmol to low pmol concentration range), as well as cell culture media analysis for amino acid and small sugar content. Peer-reviewed usage of this core by Cancer Center Members for calendar year 2000 was 73.73% of Mass Spectrometry and 48.06% for Protein Microsequencing.